1978 Johnson 9.9 choke

[ray99]

I had the carb cleaned and tried out the 9.9. Ran great for 6 hours then started losing fuel pressure. I changed all gas hoses and rebuilt the fuel pump. It runs in a barrel , but only at full and half choke. When it starts to stall, moving the choke in or out will get it going again. It won't run long in any single position. Any suggestions?
Thanks

 

[Defiant]

Re: 1978 Johnson 9.9 choke

Make sure you put the fuel pump back together right. Also having to pull the choke means its not getting enough gas.Make sure the float setting's and mixture screw's are set right .

 

[ray99]

Re: 1978 Johnson 9.9 choke

Can I test the pump by disconnecting the hose from the carb and cranking it? I'd think I should see a shot of gas doing that. Or disconnect it while it's running? The carb was working fine a few days ago, just before the fuel problem.

 

[Defiant]

Re: 1978 Johnson 9.9 choke

Yes you can unhook the hose and see if fuel comes out .Have you took the carb apart and check for dirt in the bowl that could be clogging a jet? Having the choke on means its not getting enough fuel through the carb .

 

[tashasdaddy]

Re: 1978 Johnson 9.9 choke

having to choke means it is not getting the correct fuel/air mixture into the intake and cylinders, not that the carb is not getting fuel, but it could, be part of the problem.

if you have not changed all fuel lines, tank to carbs, do so with alcohol resistant fuel lines. ethanol eats the inside of the old fuel lines, and then the interior sluffs off, clogging the jets in the carbs.

 

[wejsunek]

Re: 1978 Johnson 9.9 choke

If carb and fuel line are ok.. let's check a cylinders presure..may be the top or down engine seals are in bad conditions ..
Sorry for my poor ennglish
andrew(Poland)

 

[npd4432]

Re: 1978 Johnson 9.9 choke

Check out this website, very informative about the 9.9 and 15 HP models.

http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

 

[film495]

Re: 1978 Johnson 9.9 choke

carb, your float is sticking or adjusted wrong; or you had some gunk from the lines plug your carb again; probably the high speed needle. I'd add a little fuel filter between the pump and the carb; unscrew the high speed needle to see if any pieces of fuel line come out with the gas that will run out. then try it again - if that doesn't work - I'd bet you're float is sticking or not set to level correctly.